Display panel and method for manufacturing the same

ABSTRACT

A display panel including first and second sub pixel electrodes, a first light emitting unit, first and second charge generation layers, a second light emitting unit, and an upper electrode. The first light emitting unit is provided with a first contact hole. The first charge generation layer includes a first contact part being in the first contact hole and coupled to a portion of the first sub pixel electrode exposed by the first contact hole, and a first extension part extending from the first contact part and being on the first light emitting unit. The second charge generation layer and the second light emitting unit are provided with a second contact hole. The upper electrode includes a first upper electrode part being in the second contact hole and coupled to a second contact part of the second charge generation layer exposed by the second contact hole.

CROSS-REFERENCE TO RELATED APPLICATION

This patent application claims priority to and the benefit of KoreanPatent Application No. 10-2016-0068368, filed on Jun. 1, 2016, theentire content of which is hereby incorporated by reference.

BACKGROUND

One or more aspects of embodiments of the present disclosure hereinrelates to a display panel and a method for manufacturing the same, andmore particularly, to a display panel having improved efficiency and amethod for manufacturing the same.

Organic light emitting devices may be self-emitting devices that have awide viewing angle and superior contrast. In addition, organic lightemitting devices may have a rapid response time, high brightness, andlow driving voltage.

An example organic light emitting device includes an anode and acathode, and a hole transporting layer, a light emitting layer, and anelectron transporting layer, which are successively disposed (e.g.,positioned) on the anode, between the anode and the cathode. Forexample, the hole transporting layer, the light emitting layer, and theelectron transporting layer may be organic thin films, each of which isformed of an organic compound.

When different voltages are respectively applied to the anode and thecathode of the organic light emitting device, holes injected from theanode move to the light emitting layer via the hole transporting layer,and electrons injected from the cathode move to the light emitting layervia the electron transporting layer. The holes and the electrons arethen coupled in the light emitting layer to generate excitons. Theexcitons return from an excited state to a ground state to generatelight.

SUMMARY

One or more aspects of embodiments of the present disclosure aredirected toward a display panel having improved efficiency and a methodfor manufacturing the same.

An embodiment of the inventive concept provides a display panel that mayinclude: a base substrate; a first sub pixel electrode on the basesubstrate; a second sub pixel electrode on the base substrate and spacedapart from the first sub pixel electrode when viewed in plane; a firstlight emitting unit on the first and second sub pixel electrodes, thefirst light emitting unit being provided with a first contact hole; afirst charge generation layer including a first contact part and a firstextension part extending from the first contact part, the first contactpart being in the first contact hole and being coupled to a portion ofthe first sub pixel electrode exposed by the first contact hole, and thefirst extension part being on the first light emitting unit; a secondcharge generation layer on the first light emitting unit and overlappingthe second sub pixel electrode when viewed in plane, the second chargegeneration layer being insulated from the first charge generation layer;a second light emitting unit on the first and second charge generationlayers, the second light emitting unit and the second charge generationlayer together being provided with a second contact hole; and an upperelectrode including a first upper electrode part and a second upperelectrode part extending from the first upper electrode part, the firstupper electrode part being in the second contact hole and being coupledto a second contact part of the second charge generation layer exposedby the second contact hole, and the second upper electrode part being onthe second light emitting unit.

In an embodiment, when viewed in plane, the first and second chargegeneration layers may be spaced apart from each other.

In an embodiment, when viewed in a cross-section, the first and secondcharge generation layers may be on the same layer.

In an embodiment, when viewed in plane, the first extension part mayoverlap the second upper electrode part.

In an embodiment, the display panel may further include a pixel defininglayer configured to cover a portion of the first sub pixel electrode,wherein at least a portion of the first extension part may be on thepixel defining layer.

In an embodiment, the first contact part may be directly coupled to aportion of the first sub pixel electrode.

In an embodiment, the second light emitting unit between the firstextension part and the second upper electrode part may be configured togenerate an electric field, and the second light emitting unit may beconfigured to generate light after being excited by the electric field,and the first extension part may be configured to have substantially thesame potential as the first sub pixel electrode.

In an embodiment, the second charge generation layer may further includea second extension part extending from the second contact part tooverlap the second sub pixel electrode when viewed in plane.

In an embodiment, when viewed in plane, the second upper electrode partmay overlap the second extension part.

In an embodiment, the display panel may further include a pixel defininglayer configured to cover a portion of the second sub pixel electrode,wherein at least a portion of the second extension part may be on thepixel defining layer.

In an embodiment, an inclined surface of the second contact part exposedby the second contact hole, may be directly coupled to the first upperelectrode part.

In an embodiment, the first light emitting unit between the secondextension part and the second sub pixel electrode may be configured togenerate an electric field, and the first light emitting unit may beconfigured to generate light after being excited by the electric field,and the second upper electrode part may be configured to havesubstantially the same potential as the second extension part.

In an embodiment, the display panel may further include a third subpixel electrode disposed to be spaced apart from the first and secondsub pixel electrodes when viewed in plane, wherein the second chargegeneration layer may further include a third extension part extendingfrom the second contact part to overlap the third sub pixel electrodewhen viewed in plane.

In an embodiment, the display panel may further include first and secondcolor filters respectively configured to transmit light having colorsdifferent from each other, wherein, when viewed in plane, the firstcolor filter may overlap the first sub pixel electrode, and when viewedin plane, the second color filter may overlap the second sub pixelelectrode.

In an embodiment, the display panel may further include an auxiliaryline between the second contact part and the base substrate, wherein thefirst upper electrode part may be coupled to the auxiliary line throughthe second contact hole.

In an embodiment, the display panel may further include a fourth subpixel electrode spaced apart from the first to third sub pixelelectrodes when viewed in plane and a third charge generation layeroverlapping the fourth sub pixel electrode when viewed in plane, whereinthe third charge generation layer may be insulated from the first andsecond charge generation layers and may be between the first and secondlight emitting units.

In an embodiment, at least one of the first and second charge generationlayers may include one or more inorganic materials selected from Ag, Mg,Yb, Al, Ca, Li, and Cs.

In an embodiment of the inventive concept, a method for manufacturing adisplay panel includes: providing a first sub pixel electrode on a basesubstrate; providing a second sub pixel electrode on the base substrateand spaced apart from the first sub pixel electrode when viewed inplane; providing first light emitting unit on the first and second subpixel electrodes; providing a first contact hole in the first lightemitting unit to expose the first sub pixel electrode; providing a firstcharge generation layer on the first light emitting unit and the firstsub pixel electrode and coupling the first sub pixel electrode to thefirst charge generation layer through the first contact hole; providinga second charge generation layer on the first light emitting unit andspaced apart from the first charge generation layer when viewed inplane; providing a second light emitting unit on the first and secondcharge generation layers; providing a second contact hole in the secondlight emitting unit and the second charge generation layer; andproviding an upper electrode in the second contact hole and on thesecond light emitting unit and coupling a portion of the second chargegeneration layer exposed by the second contact hole to the upperelectrode through the second contact hole.

In an embodiment, the method may further include providing a third subpixel electrode on the base substrate, wherein the third sub pixelelectrode may be spaced apart from the first and second sub pixelelectrodes when viewed in plane.

In an embodiment, the method may further include: providing a fourth subpixel electrode on the base substrate; and providing a third chargegeneration layer overlapping the fourth sub pixel electrode, wherein thefourth sub pixel electrode may be spaced apart from the first to thirdsub pixel electrodes when viewed in plane, and the third chargegeneration layer may be insulated from the first and second chargegeneration layers and may be between the first and second light emittingunits.

In an embodiment, when the electric field is generated in the secondlight emitting unit, the electric field may not be substantiallygenerated in the first light emitting unit.

In an embodiment, wherein when the electric field is generated in thefirst light emitting unit, the electric field may not be substantiallygenerated in the second light emitting unit.

In an embodiment, the display panel may further include a pixel circuitlayer on the base substrate and a first insulation layer on the pixelcircuit layer, wherein the third sub pixel electrode may be coupled tothe pixel circuit layer through a contact hole provided in the firstinsulation layer.

In an embodiment, the auxiliary line and the second contact hole may bebetween the second and third sub pixel electrodes, or the auxiliary lineand the second contact hole may be between the third sub pixel electrodeand an edge of the display panel.

In an embodiment, the first charge generation layer may include a lowercharge generation layer and an upper charge generation layer, wherein atleast one of the lower and upper charge generation layers may be anN-type charge generation layer, and the other one of the lower and uppercharge generation layers may be a P-type charge generation layer.

In an embodiment, the first and second charge generation layers may beconfigured to supply electrons and/or holes to the second and firstlight emitting units, respectively.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are included to provide a furtherunderstanding of the present disclosure, and are incorporated in andconstitute a part of this specification. The drawings illustrate exampleembodiments of the inventive concept and, together with the description,serve to explain principles of the inventive concept. In the drawings:

FIG. 1 is a schematic plan view of a display device according to anembodiment of the inventive concept;

FIG. 2 is a schematic plan view of pixels according to an embodiment ofthe inventive concept;

FIG. 3 is a cross-sectional view taken along line I-I′ of FIG. 2;

FIG. 4 is an enlarged cross-sectional view of a first contact hole ofFIG. 3;

FIG. 5A is an enlarged cross-sectional view of a second contact hole ofFIG. 3;

FIG. 5B is an enlarged plan view of the second contact hole of FIG. 3;

FIG. 6 is a schematic plan view of pixels according to an embodiment ofthe inventive concept;

FIG. 7 is a cross-sectional view taken along line II-II′ of FIG. 6;

FIG. 8 is a schematic plan view of pixels according to an embodiment ofthe inventive concept;

FIG. 9 is a cross-sectional view taken along line III-III′ of FIG. 8;

FIG. 10 is a schematic plan view of pixels according to an embodiment ofthe inventive concept;

FIG. 11 is a cross-sectional view taken along line IV-IV′ of FIG. 10;

FIG. 12 is a schematic plan view of pixels according to an embodiment ofthe inventive concept;

FIG. 13 is a cross-sectional view taken along line V-V′ of FIG. 12;

FIG. 14 is a schematic plan view of pixels according to an embodiment ofthe inventive concept;

FIG. 15 is a schematic plan view of pixels according to an embodiment ofthe inventive concept;

FIG. 16 is a schematic cross-sectional view of a first sub pixelaccording to an embodiment of the inventive concept; and

FIGS. 17A to 17D are cross-sectional views of tasks of a method formanufacturing a display panel according to an embodiment of theinventive concept.

DETAILED DESCRIPTION

While specific embodiments of the present disclosure have beenillustrated in the drawings and are described in the detaileddescription of the inventive concept, the present disclosure is notlimited to the specific described embodiments, and it should beunderstood that the present disclosure covers all the modifications,equivalents, and replacements within the idea and technical scope of theinventive concept.

Like reference numerals refer to like elements throughout. In thedrawings, the dimensions and size of each structure may be exaggerated,omitted, and/or schematically illustrated for convenience of descriptionand clarity. When one or more components (e.g., elements) are similar,these components may be given similar names, and in this case, adescription with respect to one component may also be applied to theother component(s) having the name similar to that of the firstcomponent.

It will be understood that although the terms “first” and “second” areused herein to describe various elements, these elements should not belimited by these terms. The terms are only used to distinguish onecomponent from other components. For example, an element referred to as“a first element” in one embodiment can be referred to as “a secondelement” in another embodiment, without departing from the scope of thepresent disclosure and appended claims. The terms of a singular form mayinclude plural forms unless stated otherwise.

The terms “include” and “comprise,” when used in this specification, mayrefer to the presence of a property, a region, a fixed number, a step, aprocess, an element and/or a component but do not exclude otherproperties, regions, fixed numbers, steps, processes, elements and/orcomponents. In the specification, it will be understood that when alayer (or film), a region, and/or a plate is referred to as being “on”another layer, region, and/or plate, it can be directly on the otherlayer, region, and/or plate, or intervening layer(s), region(s), and/orplate(s) may also be present. It will be understood that when a layer(or film), a region, and/or a plate is referred to as being “under”another layer, region, and/or plate, it can be directly under the otherlayer (or film), region, and/or plate, or intervening layer(s),region(s), and/or plate(s) may also be present.

Example embodiments of the inventive concept will be described below inmore detail with reference to the accompanying drawings.

FIG. 1 is a schematic plan view of a display device according to anembodiment of the inventive concept.

Referring to FIG. 1, a display device DD according to an embodiment ofthe inventive concept includes a display panel DP, a flexible circuitboard FPC, and a printed circuit board PCB.

The display panel DP may display an image through a display area DA. Thedisplay area DA may be driven by a control signal and image data, whichare provided from the printed circuit board PCB.

The display panel DP may include gate lines GL1 to GLn, data lines DL1to DLm, and sub pixels SPX, which are disposed (e.g., positioned) in thedisplay area DA. For example, the gate lines GL1 to GLn may be arrangedwith each other along a second direction DR2 and may each independentlyextend in a first direction DR1. The data lines DL1 to DLm cross thegate lines GL1 to GLn and are insulated from the gate lines GL1 to GLn.For example, the data lines DL1 to DLm may be arranged with each otheralong the first direction DR1 and may each independently extend in thesecond direction DR2. In the specification, a “plane” may refer to aplane (e.g., a surface) that is defined by the two axes represented bythe first and second directions DR1 and DR2 (e.g., DR1-DR2 plane). Whena surface is said to extend in a “horizontal direction,” it may extendin a direction parallel to the plane. As used herein, “viewed in theplane” or “viewed in plane” may refer to a two-dimensional plan viewpoint of reference.

In an embodiment of the inventive concept, when viewed in the plane, anon-display area NDA of the display panel DP may surround the displayarea DA. The sub pixels SPX are not disposed in the non-display areaNDA, and thus, the non-display area NDA does not display an image. Thenon-display area NDA may be defined as a bezel of the display device DD(e.g., as an element between the display area DA and the edge of thedisplay device DD).

Each of the sub pixels SPX is connected (e.g., electrically coupled) toa corresponding gate line of the gate lines GL1 to GLn and acorresponding data line of the data lines DL1 to DLm.

The sub pixels SPX may be arranged in a matrix form along the first andsecond directions DR1 and DR2 (e.g., in the DR1-DR2 plane). The subpixels SPX may be configured to display one of primary colors such asred, green, and/or blue color. However, the colors capable of beingdisplayed by the sub pixels SPX are not limited to the red, green, andthe blue colors. The sub pixels SPX may display various colors, forexample, secondary primary colors such as a white color, a yellow color,a cyan color, and/or a magenta color, in addition to the red, green,and/or blue colors.

The sub pixels SPX may together constitute a pixel PX. For example, foursub pixels SPX may constitute one pixel PX. However, an embodiment ofthe inventive concept is not limited thereto. For example, two, three,or more sub pixels SPX may constitute one pixel PX.

The pixel PX may be a device for displaying a unit image. The resolutionof the display panel DP may be determined according to the number ofpixels PX provided on the display panel DP. While only one pixel PX isillustrated in FIG. 1 for convenience of explanation, the display deviceof the present embodiments may include any suitable number of pixels.

In an embodiment of the inventive concept, the display panel DP may bean organic light emitting display panel. Each of the sub pixels SPX mayinclude an organic light emitting layer.

For example, the display panel DP may have a pair of long sides, whichare parallel to the second direction DR2, and a pair of short sidesparallel to the first direction DR1 and perpendicular to and extendingbetween the pair of long sides. In an embodiment of the inventiveconcept, the display panel DP may have a plate shape. However,embodiments of the inventive concept are not limited thereto, and thedisplay panel DP may vary in shape. For example, the display panel DPmay have an edge that is curved in at least one direction when across-section of the display panel DP is viewed or has a rounded shapewhen the display panel DP is viewed in the plane.

The flexible circuit board FPC may connect (e.g., couple) the displaypanel DP to the printed circuit board PCB. Although one flexible circuitboard FPC is illustrated in FIG. 1, embodiments of the inventive conceptare not limited thereto. For example, a plurality of flexible circuitboards FPC may be provided, and the plurality of flexible circuit boardsFPC may be arranged along an edge of the display panel DP and may extendin one direction. In an embodiment of the inventive concept, the numberof flexible circuit boards FPC may variously change.

In an embodiment of the inventive concept, the flexible circuit boardFPC may include a driving chip DC. The driving chip DC may be mounted onthe flexible circuit board FPC in the form of, for example, a tapecarrier package (TCP). The driving chip DC may include a chip thatprovides for a data driver. The driving chip DC may further include achip that provides for a gate driver. Also, the gate driver may bedisposed within the non-display area NDA.

The printed circuit board PCB may include a control unit for controllingthe display panel DP. The control unit receives input image signals andconverts data format of the input image signals to match interfacespecifications of the data driver, the gate driver, and the displaypanel DP, thereby generating the image data. The control unit outputsthe image data and the control signal. The image data may includeinformation with respect to an image to be displayed on the display areaDA.

The data driver receives each of the image data and the control signal.The data driver converts the image data into data voltages in responseto the control signal, to output the data voltages to the data lines DL1to DLm. The data voltages may be analog voltages corresponding to theimage data.

Various electronic devices that realize (e.g., utilize) the control unitmay be mounted on the printed circuit board PCB. For example, theprinted circuit board PCB may include active devices such as amicroprocessor and/or a memory chip and lines connecting the activedevices to each other, as well as passive devices such as a capacitorand/or a resistor.

FIG. 2 is a schematic plan view of the pixel according to an embodimentof the inventive concept, and FIG. 3 is a cross-sectional view takenalong line I-I′ of FIG. 2.

Referring to FIG. 2, the pixel PX according to an embodiment of theinventive concept may include first and second sub pixels SPX1 and SPX2.The first and second sub pixels SPX1 and SPX2 may be examples of the subpixels SPX illustrated in FIG. 1.

In an embodiment of the inventive concept, the first and second subpixels SPX1 and SPX2 may be a blue sub pixel and a green sub pixel,respectively. Each of the first and second sub pixels SPX1 and SPX2 mayhave an approximately rectangular (e.g., substantially rectangular)shape and may be arranged with each other along the first direction DR1.

Referring to FIG. 3, in an embodiment of the inventive concept, thedisplay panel DP may include a base substrate BS, a pixel circuit layerPC, a first insulation layer IL1, a first sub pixel electrode 110, asecond sub pixel electrode 120, organic layers disposed on the first andsecond sub pixel electrodes 110 and 120, and an upper electrode 600disposed on the organic layers. In an embodiment of the inventiveconcept, the organic layers may include a first light emitting unit 200,a first charge generation layer 300, a second charge generation layer400, and a second light emitting unit 500.

In an embodiment of the inventive concept, the layers (e.g., the basesubstrate BS, the pixel circuit layer PC, the first insulation layerIL1, the first sub pixel electrode 110, the organic layers, and theupper electrode 600) of the display panel DP that are disposed within afirst sub pixel area SPA1 when the display panel DP is viewed in theplane, may constitute the first sub pixel SPX1, and the layers of thedisplay panel DP that are disposed within a second sub pixel area SPA2may constitute the second sub pixel SPX2.

In an embodiment of the inventive concept, the base substrate BS may betransparent, for example, may be formed of or may include rigid glassand/or a polymer having flexibility.

In an embodiment of the inventive concept, the pixel circuit layer PCmay be disposed on an entire top surface of the base substrate BS (e.g.,the pixel circuit layer PC may entirely cover the top surface of thebase substrate BS). The pixel circuit layer PC may include, for example,at least two or more transistors. The pixel circuit layer PC mayinclude, for example, a switching transistor that is turned on inresponse to an applied gate signal to transmit a data voltage, and adriving transistor supplying driving current corresponding to the datavoltage received from the switching transistor to the first lightemitting unit 200.

The first insulation layer IL1 may be disposed on substantially anentire top surface of the pixel circuit layer PC. The first insulationlayer IL1 may include contact holes through which a portion of the pixelcircuit layer PC is exposed. The first insulation layer IL1 may have asingle-layer or a multi-layer structure, and may include an organicmaterial and/or an inorganic material.

In an embodiment of the inventive concept, the first and second subpixel electrodes 110 and 120 may be disposed on the first insulationlayer IL1 and spaced apart from each other in the first direction DR1.Portions of the first and second sub pixel electrodes 110 and 120 may bedisposed in the corresponding contact holes of the first insulationlayer IL1 to directly contact the pixel circuit layer PC and thusindependently receive the driving current from the pixel circuit layerPC.

The display panel DP may further include a pixel defining layer PDL. Thepixel defining layer PDL may be disposed on, for example, the first andsecond sub pixel electrodes 110 and 120 and the first insulation layerIL1. The pixel defining layer PDL may cover portions (e.g., edges) ofthe first and second sub pixel electrodes 110 and 120, while leavingportions of the first and second sub pixel electrodes 110 and 120exposed (e.g., not covered by the pixel defining layer PDL).

In an embodiment of the inventive concept, the first light emitting unit200 may be disposed on the pixel defining layer PDL and the first andsecond sub pixel electrodes 110 and 120. The first light emitting unit200 may generate, for example, first light having a first color.

In an embodiment of the inventive concept, the first charge generationlayer 300 may be disposed on the first light emitting unit 200 tooverlap the first sub pixel electrode 110 when viewed in the plane. Thefirst charge generation layer 300 may be disposed between the first andsecond light emitting units 200 and 500 to supply charges (e.g.,electrons and/or holes) to the first and second light emitting units 200and 500 of the first sub pixel SPX1 and to adjust (e.g., improve) abalance of the supplied charges. In this specification, “the first andsecond light emitting units 200 and 500 of the first sub pixel SPX1” mayrefer to portions of the first and second light emitting units 200 and500 positioned within the first sub pixel area SPA1. Hereinafter, othercomponents of the first and second sub pixels SPX1 and SPX2 may beindicated by using expressions similar thereto.

The first charge generation layer 300 may include a first contact part310 and a first extension part 320. The first contact part 310 may beconnected (e.g., coupled) to the first sub pixel electrode 110 through afirst contact hole CNT1 defined in the first light emitting unit 200.

In an embodiment of the inventive concept, the second charge generationlayer 400 may be disposed on the first light emitting unit 200 tooverlap the second sub pixel electrode 120 when viewed in the plane. Thesecond charge generation layer 400 may be disposed between the first andsecond light emitting units 200 and 500 to supply charges (e.g.,electrons and/or holes) to the first and second light emitting units 200and 500 of the second sub pixel SPX2, and may adjust (e.g., improve) abalance of the supplied charges. The second charge generation layer 400may be, for example, spaced apart from the first charge generation layer300 in the first direction DR1 and insulated from the first chargegeneration layer 300.

The second charge generation layer 400 may include a second contact part410 and a second extension part 420. The second contact part 410 may beconnected (e.g., coupled) to the upper electrode 600 through a secondcontact hole CNT2 defined in the first light emitting unit 200, thesecond charge generation layer 400, and the second light emitting unit500. The second extension part 420 may horizontally extend from thesecond contact part 410 and may overlap the upper electrode 600 and thesecond sub pixel electrode 120 when viewed in the plane. At least aportion of the second extension part 420 may be disposed to overlap thepixel defining layer PDL.

In an embodiment of the inventive concept, the light emitting unit 500may be disposed on the first and second charge generation layers 300 and400 and may entirely cover the top surfaces of the first and secondcharge generation layers 300 and 400. The second light emitting unit 500may emit, for example, second light having a second color.

In an embodiment of the inventive concept, a mixed color of the firstand second colors may be, for example, a white color, and/or the firstand second colors may complement each other. The first and second lightmay be mixed with each other to generate white light. The first andsecond colors may be, for example, a blue color and a yellow color,respectively. However, the embodiment of the inventive concept is notlimited thereto. For example, the first and second colors may be a redcolor and a green color, respectively.

The upper electrode 600 may be disposed on the second light emittingunit 500. The upper electrode 600 may include a first upper electrodepart 610 and a second upper electrode part 620. The first upperelectrode part 610 may be connected (e.g., coupled) to the secondcontact part 410 through the second contact hole CNT2. The second upperelectrode part 620 may extend from the first upper electrode part 610.The upper electrode 600 may be disposed on an entire top surface of thesecond light emitting unit 500. Thus, when viewed in the plane, thesecond upper electrode part 620 may overlap the first and second subpixel electrodes 110 and 120.

In an embodiment of the inventive concept, the display panel DP mayfurther include a color filter. In an embodiment of the inventiveconcept, the color filter may be disposed on (e.g., over) the upperelectrode 600. The color filter may be, for example, formed on the upperelectrode 600 in the form of a layer and then laminated or disposed onan upper substrate (not shown) facing the base substrate BS. Also, in anembodiment of the inventive concept, when the display panel DP is abottom emission-type display panel (e.g., bottom emission displaypanel), the color filter may be disposed on a layer that is defined(e.g., positioned) between the first sub pixel electrode 110 and thebase substrate BS.

In an embodiment of the inventive concept, the color filter may includefirst and second color filters CF1 and CF2. The first and second colorfilters CF1 and CF2 may transmit colors different from each othertherethrough. The second color filter CF2 may be disposed in the secondsub pixel area SPA2 to correspond to a second light emitting area EA2defined on the second sub pixel electrode 120, and may be, for example,a green color filter. The first color filter CF1 may be disposed in thefirst sub pixel area SPA1 to correspond to a first light emitting areaEA1 defined on the first sub pixel electrode 110, and may be, forexample, a gray color filter. The gray color filter may block (orreduce) the transmission of a specific color therethrough and may reduceexternal light reflection by the first sub pixel electrode 110. Thefirst color filter CF1 may be, for example, omitted.

Each of the first and second charge generation layers 300 and 400 hasconductivity. In an embodiment of the inventive concept, the first andsecond charge generation layers 300 and 400 may include one or moreinorganic materials selected from, for example, Ag, Mg, Yb, Al, Ca, Li,and Cs.

Each of the first and second sub pixel electrodes 110 and 120 and theupper electrode 600 may be formed of a conductive material. In someembodiments, each of the first and second sub pixel electrodes 110 and120 and the upper electrode 600 may be a transparent electrode, atranslucent electrode, an opaque electrode, or a reflective electrode.Also, each of the first and second sub pixel electrodes 110 and 120 andthe upper electrode 600 may have a single-layered structure formed of asingle material, a single-layered structure formed of a plurality ofmaterials different from each other, or a multi-layered structureincluding a plurality of layers formed of a plurality of materialsdifferent from each other.

In an embodiment of the inventive concept, when each of the first andsecond sub pixel electrodes 110 and 120 and the upper electrode 600 is atransparent electrode or a translucent electrode, each of the first andsecond sub pixel electrodes 110 and 120 and the upper electrode 600 mayinclude, for example, optical thin Li, Ca, LiF/Ca, LiF/Al, Al, Mg, BaF,Ba, Ag, or a combination or mixture thereof (e.g., a mixture of Ag andMg) or may include transparent metal oxide, for example, indium tinoxide (ITO), indium zinc oxide (IZO), zinc oxide (ZnO), indium tin zincoxide (ITZO), Mo, and/or Ti.

In an embodiment of the inventive concept, when each of the first andsecond sub pixel electrodes 110 and 120 and the upper electrode 600 is areflective electrode, each of the first and second sub pixel electrodes110 and 120 and the upper electrode 600 may include, for example,optical thick Ag, Mg, Al, Pt, Pd, Au, Ni, Nd, Ir, Cr, Li, Ca, LiF/Ca,LiF/Al, Mo, Ti, or a combination or mixture thereof (e.g., a mixture ofAg and Mg).

In an embodiment of the inventive concept, each of the first and secondsub pixels SPX1 and SPX2 may be a bottom emission-type sub pixel or atop emission-type sub pixel (e.g., a bottom emission sub pixel or a topemission sub pixel). When each of the first and second sub pixels SPX1and SPX2 is a bottom emission sub pixel, each of the first and secondsub pixel electrodes may be a transparent or a translucent electrode,the upper electrode 600 may be a reflective electrode, and the light maybe emitted to the outside through the first and second sub pixelelectrodes 110 and 120. When each of the first and second sub pixelsSPX1 and SPX2 is a top emission sub pixel, each of the first and secondsub pixel electrodes 110 and 120 may be a reflective electrode, theupper electrode 600 may be a transparent or a translucent electrode, andthe light may be emitted to the outside through the upper electrode 600.

In an embodiment of the inventive concept, each of the first and secondsub pixels SPX1 and SPX2 may have a non-inverted structure or aninverted structure. When each of the first and second sub pixels SPX1and SPX2 has the non-inverted structure, each of the first and secondsub pixel electrodes 110 and 120 may be an anode, the upper electrode600 may be a cathode, and a voltage applied to the first and second subpixel electrodes 110 and 120 may be greater than that applied to theupper electrode 600. On the other hand, when each of the first andsecond sub pixels SPX1 and SPX2 has the inverted structure, each of thefirst and second sub pixel electrodes 110 and 120 may be a cathode, theupper electrode 600 may be an anode, and a voltage applied to the firstand second sub pixel electrodes 110 and 120 may be less than thatapplied to the upper electrode 600.

FIG. 4 is an enlarged cross-sectional view of the first contact hole ofFIG. 3.

The first contact hole CNT1 may be defined in the first light emittingunit 200. The first contact hole CNT1 may be defined, for example, onthe first sub pixel electrode 110. The first contact hole CNT1 mayexpose a portion of the first sub pixel electrode 110 and an inclinedsurface 201 of the first light emitting unit 200.

In this specification, the expression “the contact hole is defined in alayer” may refer to a space formed by removing a portion of the layer toform a contact hole. Thus, the first contact hole CNT1 may be defined asan empty space (a region with a dot pattern shading in FIG. 4) formed byremoving a portion of the first light emitting unit 200.

In an embodiment, the first contact part 310 is disposed in the firstcontact hole CNT1. The first contact part 310 may refer to only theportion of the first charge generation layer 300 that is disposed in thefirst contact hole CNT1, (e.g., the portion of the first chargegeneration layer corresponding to a region that is surrounded by theinclined surface 201 of the first light emitting unit 200 and a topsurface of the first sub pixel electrode 110).

The first contact part 310 may be connected to the first sub pixelelectrode 110 that is exposed by the first contact hole CNT1. The firstcontact part 310 may, for example, directly contact the top surface ofthe first sub pixel electrode 110. The first contact part 310 mayreceive driving current and a first pixel voltage from the first subpixel electrode 110.

The first extension part 320 may extend from the first contact part 310and may be disposed on the first light emitting unit 200. The firstextension part 320 may receive the driving current and the first pixelvoltage from the first contact part 310.

FIG. 5A is an enlarged cross-sectional view of the second contact holeof FIG. 3, and FIG. 5B is an enlarged plan view of the second contacthole of FIG. 3.

In FIGS. 5A and 5B, the second contact hole CNT2 may be designated by adot pattern shading. It will be understood by those skilled in the artthat the dot pattern shading may, but does not necessarily, indicate anempty space. In FIGS. 5A and 5B, for convenience of illustration of thesecond contact hole CNT2 and an inclined surface 411 of the secondcontact part 410, certain components may be omitted. For example, theupper electrode 600 may be omitted in FIG. 5B.

Referring to FIGS. 5A and 5B, the second contact hole CNT2 may bedefined in the first light emitting unit 200, the second chargegeneration layer 400, and the second light emitting unit 500.

The second contact hole CNT2 may expose a portion of the firstinsulation layer IL1, the inclined surface 201 of the first lightemitting unit 200, the inclined surface 411 of the second contact part410, and an inclined surface 501 of the second light emitting unit 500.

In an embodiment of the inventive concept, the upper electrode 600 mayinclude the first upper electrode part 610 and the second upperelectrode part 620. The first upper electrode part 610 may be disposedin the second contact hole CNT2. The first upper electrode 610 may beconnected (e.g., coupled) to the second contact part 410. The firstupper electrode 610 may, for example, directly contact the inclinedsurface 411 of the second contact part 410. The second contact part 410may transmit the driving current to the upper electrode 600.

Referring again to FIG. 3, the first pixel voltage may be applied to thefirst sub pixel electrode 110, and an upper voltage may be applied tothe upper electrode 600. The first pixel voltage may be transmitted tothe first extension part 320 disposed within the first light emittingarea EA1 through the first contact part 310. As a result, a firstelectric field EF1 may be formed between the first extension part 320and the upper electrode 600 to correspond to the first light emittingarea EA1.

The first pixel voltage may be, for example, greater than the uppervoltage. Thus, first driving current DC1 may flow along a first currentpath that is defined to be along the first sub pixel electrode 110, thefirst contact part 310, the first extension part 320, the second lightemitting unit 500 of the first sub pixel SPX1, and the second upperelectrode part 620 of the first sub pixel SPX1.

The second light emitting unit 500 of the first sub pixel SPX1 maygenerate second light L2 by the first driving current DC1 and the firstelectric field EF1. The second light L2 may pass through the first colorfilter CF1 and then be emitted upward (e.g., outward). When the firstcolor filter CF1 is the gray color filter, the second color (e.g., bluecolor) of the second light L2 passing through the first color filter CF1may not change.

As described above, when the first extension part 320 functions as theanode of the first sub pixel SPX1, the first electric field EF1 may beapplied to only the second light emitting unit 500 of the first subpixel SPX1. Since potential of the first extension part 320 issubstantially the same as that of the first sub pixel electrode 110, anelectric field may not be substantially generated in the first lightemitting unit 200 of the first sub pixel SPX1. Thus, the driving voltageof the first sub pixel SPX1 may be reduced to improve efficiency of thefirst sub pixel SPX1.

Similarly, the second sub pixel may be improved in efficiency. Forexample, a second pixel voltage may be applied to the second sub pixelelectrode 120, and the upper voltage may be applied to the upperelectrode 600. The upper voltage may be transmitted to the secondextension part 420 disposed within the second light emitting area EA2through the second contact part 410. As a result, a second electricfield EF2 may be formed between the second extension part 420 and thesecond sub pixel electrode 120 to correspond to the second lightemitting area EA2.

The second pixel voltage may be, for example, greater than the uppervoltage. Thus, second driving current DC2 may flow along a secondcurrent path that is defined to be along the second sub pixel electrode120, the first light emitting unit 200, the second extension part 420,the second contact part 410, and the first upper electrode part 610.

The first light emitting unit 200 of the second sub pixel SPX2 maygenerate the first light L1 by the second driving current DC2 and thesecond electric field EF2. The first light L1 may pass through thesecond color filter CF2 and then be emitted upward (e.g., outward). Inan embodiment of the inventive concept, when the second color filter CF2is the green color filer, the first color (e.g., yellow color) of thefirst light L1 passing through the second color filter CF2 may changeinto a green color.

As described above, when the second extension part 420 functions as thecathode of the second sub pixel SPX2, the second electric field EF2 maybe applied to only the first light emitting unit 200 of the second subpixel SPX2. Since potential of the upper electrode 600 is substantiallythe same as that of the second extension part 420, an electric field maynot be substantially generated in the second light emitting unit 500 ofthe second sub pixel SPX2. Thus, the driving voltage of the second subpixel SPX2 may be reduced to improve efficiency of the second sub pixelSPX2.

FIG. 6 is a schematic plan view of a pixel according to an embodiment ofthe inventive concept, and FIG. 7 is a cross-sectional view taken alongline II-II′ of FIG. 6.

Since a pixel PX of FIG. 6 is similar to the pixel PX of FIG. 3, thefollowing description will mainly focus on the differences with respectto an additional third sub pixel SPX3, and duplicative descriptions ofthe elements same as those described above in connection with FIG. 3will not be provided.

Referring to FIG. 6, the pixel PX according to an embodiment of theinventive concept may further include the third sub pixel SPX3. Thethird sub pixel SPX3 may be an example of the sub pixels SPX illustratedin FIG. 1.

In an embodiment of the inventive concept, the third sub pixel SPX3 maybe a sub pixel having a color different from those of the first andsecond sub pixels SPX1 and SPX2. The third sub pixel SPX3 may be, forexample, a red sub pixel. The first to third sub pixels SPX1 to SPX3 maybe successively arranged with each other along the first direction DR1.The second contact hole CNT2 may be disposed, for example, between thesecond and third sub pixels SPX2 and SPX3 when viewed in the plane.

Referring to FIG. 7, the display panel DP may further include a thirdsub pixel electrode 130. The third sub pixel electrode 130 may bedisposed on the first insulation layer IL1. The third sub pixelelectrode 130 may be spaced apart from the first and second sub pixelelectrodes 110 and 120 when viewed in the plane. A portion of the thirdsub pixel electrode 130 may be disposed in the contact hole defined inthe first insulation layer IL1 to directly contact the pixel circuitlayer PC and independently receive the driving current from the pixelcircuit layer PC.

In an embodiment of the inventive concept, a portion of the first lightemitting unit 200 may extend and be disposed on the third sub pixelelectrode 130.

In an embodiment of the inventive concept, the second charge generationlayer 400 may further include a third extension part 430. The thirdextension part 430 may extend from the second contact part 410 tooverlap the third sub pixel electrode 130 when viewed in the plane. Thethird extension part 430 may, for example, extend from the secondcontact part 410 in a third direction DR3 that is opposite to the firstdirection DR1.

The third extension part 430 may be disposed on the first light emittingunit 200 to correspond to a third sub pixel area SPA3. The thirdextension part 430 may be disposed between first and second lightemitting units 200 and 500 of the third sub pixel SPX3 to supply charges(e.g., electrons and/or holes) to the first and second light emittingunits 200 and 500 of the third sub pixel SPX3, and may adjust a balanceof the supplied charges.

In an embodiment of the inventive concept, a portion of the second lightemitting unit 500 may extend and be disposed on the third extension part430 and may cover an entire top surface of the third extension part 430.

The second extension part 620 may extend from the first contact part 610to overlap the third sub pixel electrode 130 when viewed in the plane.

The color filter may further include a third color filter CF3. The thirdcolor filter CF3 may transmit a color different from that transmittedthrough the second color filter CF2. The third color filter CF3 may bedisposed in the third sub pixel area SPA3 to correspond to a third lightemitting area EA3 defined on the third sub pixel electrode 130 and maybe, for example, a red color filter.

According to an embodiment of the inventive concept, the third sub pixelSPX3 may be improved in efficiency. For example, a third pixel voltagemay be applied to the third sub pixel electrode 130, and the uppervoltage may be applied to the upper electrode 600. The upper voltage maybe transmitted to the third extension part 430 disposed within the thirdlight emitting area EA3 through the second contact part 410. As aresult, a third electric field EF3 may be formed between the thirdextension part 430 and the third sub pixel electrode 130 to correspondto the third light emitting area EA3.

The third pixel voltage may be, for example, greater than the uppervoltage. Thus, third driving current DC3 may flow along a third currentpath that is defined to be along the third sub pixel electrode 130, thefirst light emitting unit 200, the third extension part 430, the secondcontact part 410, and the first upper electrode part 610.

The first light emitting unit 200 of third second sub pixel SPX3 maygenerate the first light L1 by the third driving current DC3 and thethird electric field EF3. The first light L1 may pass through the thirdcolor filter CF3 and then be emitted upward (e.g., outward). In anembodiment of the inventive concept, when the third color filter CF3 isthe red color filer, the first color (e.g., yellow color) of the firstlight L1 passing through the third color filter CF3 may change into ared color.

As described above, when the third extension part 430 functions as thecathode of the third sub pixel SPX3, the third electric field EF3 may beapplied to only the first light emitting unit 200 of the third sub pixelSPX3. Since potential of the upper electrode 600 is substantially thesame as that of the third extension part 430, an electric field may notbe substantially generated in the second light emitting unit 500 of thethird sub pixel SPX3. Thus, the driving voltage of the third sub pixelSPX3 may be reduced to improve efficiency of the third sub pixel SPX3.

FIG. 8 is a schematic plan view of a pixel according to an embodiment ofthe inventive concept, and FIG. 9 is a cross-sectional view taken alongline III-III′ of FIG. 8.

Since a pixel PX of FIG. 8 is similar to the pixel PX of FIG. 6, thefollowing description will mainly focus on the differences with respectto an additional auxiliary line 100, and duplicative descriptions of theelements same as those described above in connection with FIG. 6 willnot be provided.

Referring to FIGS. 8 and 9, the display panel DP according to anembodiment of the inventive concept further includes the auxiliary line100.

In an embodiment of the inventive concept, when viewed in the plane, theauxiliary line 100 may be disposed between the second and third subpixels SPX2 and SPX3 to extend in the second direction DR2. Although notshown, a plurality of the auxiliary lines 100 may be provided. Theplurality of auxiliary lines may be arranged with each other along thefirst direction DR1 to either correspond to each pixel or correspond toevery two or more of the pixels PX.

In an embodiment of the inventive concept, the auxiliary line 100 may bedisposed between the first insulation layer IL1 and the first lightemitting unit 200. The second contact hole CNT2 may expose, for example,a top surface of the auxiliary line 100. Thus, the first upper electrodepart 610 may be connected (e.g., coupled) to the auxiliary line 100. Thefirst upper electrode part 610 may, for example, directly contact theexposed top surface of the auxiliary line 100.

The auxiliary line 100 may prevent or reduce an IR-drop from occurringin the display panel DP. For example, when the upper electrode 600 isdisposed on (e.g., over) an entire top surface of the base substrate BS,the IR-drop may occur in the upper electrode 600 in the horizontaldirection, and brightness of the pixel PX may change according to aposition of the display panel DP. To prevent or reduce the IR-drop fromoccurring, the upper electrode 600 may be connected to the auxiliaryline 100. Since the auxiliary line 100 is connected (e.g., coupled) tothe upper electrode 600, the total resistance may be reduced to preventor reduce the occurrence of the IR-drop in the upper electrode 600. As aresult, as the occurrence of the IR-drop is reduced, the drivingvoltages of the second and third sub pixels SPX2 and SPX3 may beimproved to improve efficiency of the second and third sub pixels SPX2and SPX3.

FIG. 10 is a schematic plan view of a pixel according to an embodimentof the inventive concept, and FIG. 11 is a cross-sectional view takenalong line IV-IV′ of FIG. 10.

Since a pixel PX of FIG. 10 is similar to the pixel PX of FIG. 6, thefollowing description will mainly focus on the differences with respectto the second contact hole CNT2, and duplicative descriptions of theelements same as those described above in connection with FIG. 6 willnot be provided.

Referring to FIGS. 10 and 11, in an embodiment of the inventive concept,the second contact hole CNT2 and the auxiliary line 100 may be spacedapart from the third sub pixel electrode 130 in the third direction DR3.

Since in the present embodiment, the second contact hole CNT2 is notdisposed between the second and third sub pixels SPX2 and SPX3, adistance between the second and third sub pixels SPX2 and SPX3 may bereduced. Also, the auxiliary line 100 may be widened in line width, andthus the auxiliary line 100 may be effectively (or suitably) reduced inresistance, and the IR drop of the upper electrode 600 may be preventedor substantially reduced.

FIG. 12 is a schematic plan view of the pixel according to an embodimentof the inventive concept, and FIG. 13 is a cross-sectional view takenalong line V-V′ of FIG. 12.

Since a pixel PX of FIG. 12 is similar to the pixel PX of FIG. 6, thefollowing description will mainly focus on the differences with respectto an additional fourth sub pixel SPX4, and duplicative descriptions ofthe elements same as those described above in connection with FIG. 6will not be provided.

Referring to FIG. 12, the pixel PX according to an embodiment of theinventive concept may further include the fourth sub pixel SPX4. Thefourth sub pixel SPX4 may be an example of the sub pixels SPXillustrated in FIG. 1.

In an embodiment of the inventive concept, the fourth sub pixel SPX4 maybe a sub pixel having a color different from those of the first to thirdsub pixels SPX1 to SPX3. The fourth sub pixel SPX4 may be, for example,a white sub pixel. The first to fourth sub pixels SPX1 to SPX4 may besuccessively arranged in the first direction DR1. The first contact holeCNT1 may be disposed, for example, between the first and fourth subpixels SPX1 and SPX4 when viewed in the plane.

Referring to FIG. 13, the display panel DP may further include a fourthsub pixel electrode 140. The fourth sub pixel electrode 140 may bedisposed on the first insulation layer IL1. The fourth sub pixelelectrode 140 may be spaced apart from the first sub pixel electrode 110in first direction DR1 when viewed in the plane. A portion of the fourthsub pixel electrode 140 may be disposed in the contact hole defined inthe first insulation layer IL1 to directly contact the pixel circuitlayer PC and independently receive the driving current from the pixelcircuit layer PC.

In an embodiment of the inventive concept, a portion of the first lightemitting unit 200 may extend and be disposed on the fourth sub pixelelectrode 140.

In an embodiment of the inventive concept, the display panel DP mayfurther include a third charge generation layer 700. The third chargegeneration layer 700 may not overlap the first and second chargegeneration layers 300 and 400 when viewed in the plane and may beinsulated from the first and second charge generation layers 300 and400.

The third charge generation layer 700 may be disposed on the first lightemitting unit 200 to correspond to a fourth sub pixel area SPA4. Thethird charge generation layer 700 may be disposed between first andsecond light emitting units 200 and 500 of the fourth sub pixel SPX4 tosupply charges (e.g., electrons and/or holes) to the first and secondlight emitting units 200 and 500 of the fourth sub pixel SPX4 and toadjust a balance of the supplied charges.

In an embodiment of the inventive concept, a portion of the second lightemitting unit 500 may extend and be disposed on the third chargegeneration layer 700 and may cover an entire top surface of the thirdcharge generation layer 700.

A portion of the second upper electrode part 620 may overlap the fourthsub pixel electrode 140 when viewed in the plane.

The color filter may further include a fourth color filter CF4. Thefourth color filter CF4 may be disposed in the fourth sub pixel areaSPA4 to correspond to a fourth light emitting area EA4 defined on thefourth sub pixel electrode 140 and may be, for example, a gray colorfilter. In some embodiments, the fourth color filter CF4 may not beprovided.

A fourth pixel voltage may be applied to the fourth sub pixel electrode140, and the upper voltage may be applied to the second upper electrodepart 620 of the upper electrode 600. As a result, a fourth electricfield EF4 may be formed between the fourth sub pixel electrode 140 andthe second upper electrode part 620 to correspond to the fourth lightemitting area EA4.

The fourth pixel voltage may be, for example, greater than the uppervoltage. Thus, fourth driving current DC4 may flow along a fourthcurrent path that is defined to be along the fourth sub pixel electrode140, the first light emitting unit 200, the third charge generationlayer 700, and the second upper electrode part 620.

Both the first and the second light emitting units 200 and 500 of thefourth sub pixel SPX4 may emit light to generate the first and secondlights L1 and L2 by the fourth driving current DC4 and the fourthelectric field EF4. The first and second lights L1 and L2 may be mixedwith each other to generate white light. The white light may passthrough the fourth color filter CF4 and then be emitted upward (e.g.,outward). When the fourth color filter CF4 is the gray color filter, thecolor (e.g., white color) of the white light passing through the fourthcolor filter CF4 may not change.

FIG. 14 is a schematic plan view of a pixel according to an embodimentof the inventive concept.

Since a pixel PX of FIG. 14 is similar to the pixel PX of FIG. 6, thefollowing description will mainly focus on the differences with respectto the modified first and second contact holes CNT1 and CNT2, andduplicative descriptions of the elements same as those described abovein connection with FIG. 6 will not be provided.

Referring to FIG. 14, in an embodiment of the inventive concept, thefirst contact hole CNT1 may be defined (e.g., positioned) in a centralportion of the first sub pixel area SPA1. Here, a central portion of thefirst charge generation layer 300 may be connected (e.g., coupled) tothe first sub pixel electrode 110 through the first contact hole CNT1.Thus, a first pixel voltage may be uniformly (or substantiallyuniformly) distributed in the first charge generation layer 300.

In an embodiment of the inventive concept, the second contact hole CNT2may be defined in a center of the second charge generation layer 400.Here, a central portion of the second charge generation layer 400 may beconnected (e.g., coupled) to the upper electrode (see e.g., referencenumeral 600 of FIG. 3) through the second contact hole CNT2. Thus, theupper voltage may be uniformly (or substantially uniformly) distributedin the second charge generation layer 400.

FIG. 15 is a schematic plan view of a pixel according to an embodimentof the inventive concept.

Since a pixel PX of FIG. 15 is similar to the pixel PX of FIG. 6, thefollowing description will mainly focus on the differences with respectto the modified first and second contact holes CNT1 and CNT2, andduplicative descriptions of the elements same as those described abovein connection with FIG. 6 will not be provided. Referring to FIG. 15,each of the first and second contact holes CNT1 and CNT2 may be providedin plurality.

The plurality of the first and second contact holes CNT1 and CNT2 mayeach independently be arranged with each other, for example, along thesecond direction DR2. However, the embodiment of the inventive conceptis not limited thereto. For example, the first and second contact holesCNT1 and CNT2 may each independently be arranged in the form of a matrixin the first and second directions DR1 and DR2.

When each of the first and second contact holes CNT1 and CNT2 isprovided in plurality, the distribution of the first pixel voltage inthe first charge generation layer 300 and the distribution of the uppervoltage in the second charge generation layer 400 may be uniform (orsubstantially uniform).

FIG. 16 is a schematic cross-sectional view of the first sub pixelaccording to an embodiment of the inventive concept.

Referring to FIG. 16, the first light emitting unit 200 may include afirst hole control layer HCL1, a first light emitting layer EML1, and afirst electron control layer ECL1. The second light emitting unit 500may include a second hole control layer HCL2, a second light emittinglayer EML2, and a second electron control layer ECL2.

The first and second light emitting layers EML1 and EML2 may be disposedbetween the first sub pixel electrode 110 and the upper electrode 600.In an embodiment of the inventive concept, each of the first and secondlight emitting layers EML1 and EML2 may include a host material and adopant material. For example, each of the first and second lightemitting layers EML1 and EML2 may be formed by doping a phosphorescentor fluorescent material into the host material.

The host material is not specifically limited so long as the hostmaterial is a suitable material capable of being used in an organiclight emitting device. For example, the host material may includetris(8-hydroxyquinolino)aluminum (Alq3),4,4′-bis(N-carbazolyl)-1,1′-biphenyl (CBP), poly(n-vinylcabazole) (PVK),9,10-di(naphthalene-2-yl)anthracene (ADN),4,4′,4″-Tris(carbazol-9-yl)-triphenylamine (TCTA),1,3,5-tris(N-phenylbenzimidazole-2-yl)benzene (TPBi),3-tert-butyl-9,10-di(naphth-2-yl)anthracene (TBADN), distyrylarylene(DSA), 4,4′-bis(9-carbazolyl)-2,2′-dimethyl-biphenyl (CDBP), and/or2-methyl-9,10-bis(naphthalen-2-yl)anthracene (MADN).

A color of light emitted from a corresponding light emitting layer maybe determined by the combination of the host material and the dopantmaterial. For example, when the corresponding light emitting layer emitslight having a red color, the corresponding light emitting layer mayinclude a phosphorescent material includingtris(dibenzoylmethanato)phenanthoroline europium (PBD:Eu(DBM)3(Phen))and/or perylene.

The dopant material included in the corresponding light emitting layermay be, for example, a metal complex such asbis(1-phenylisoquinoline)acetylacetonate iridium (PIQIr(acac)),bis(1-phenylquinoline)acetylacetonate iridium (PQIr(acac)),tris(1-phenylquinoline)iridium (PQIr), and/or octaethylporphyrinplatinum (PtOEP), and/or an organometallic complex.

For example, when the corresponding light emitting layer emits lighthaving a green color, the corresponding light emitting layer may includea fluorescent material including tris(8-hydroxyquinolino)aluminum(Alq3). Here, the dopant material included in the corresponding lightemitting layer may be, for example, a metal complex such asfac-tris(2-phenylpyridine)iridium (Ir(ppy)3), and/or an organometalliccomplex.

For example, when the corresponding light emitting layer emits lighthaving a blue color, the corresponding light emitting layer may includea fluorescent material including at least one selected from spiro-DPVBi,spiro-6P, distyryl-benzene (DSB), distyryl-arylene (DSA), polyfluorene(PFO)-based polymer and poly(p-phenylene vinylene (PPV)-based polymer.Here, the dopant material included in the corresponding light emittinglayer may be, for example, a metal complex such as (4,6-F2ppy)2Irpic,and/or an organometallic complex.

The first light emitting layer EML1 may generate light having arelatively short wavelength when compared to that of the second lightemitting layer EML2. As described above, the first light may be bluelight and have a wavelength ranging from about 450 nm to about 595 nm.

As described above, the second light may be yellow light and have awavelength ranging from about 570 nm to about 590 nm.

However, the above-described description is merely an exampleembodiment, and the present inventive concept is not limited thereto.The first and second light emitting layers EML1 and EML2 according to anembodiment of the inventive concept may be designed to generate lighthaving various colors and also may not be limited to any one embodiment.

Each of the first and second light emitting layers EML1 and EML2 may beformed by using various methods such as a vacuum deposition method, aspin coating method, a casting method, a Langmuir-Blodgett (LB) method,an inject printing method, a laser printing method, and/or a laserinduced thermal imaging (LITI) method.

The first charge generation layer 300 may be disposed between the firstand second light emitting layers EML1 and EML2 to improve currentefficiency and optical efficiency of the first sub pixel SPX1. When avoltage is applied to the first charge generation layer 300, a complexmay be formed by oxidation-reduction reaction to generate charges.

In an embodiment of the inventive concept, the first charge generationlayer 300 may include lower and upper charge generation layers 301 and302, which may be successively laminated. The lower and upper chargegeneration layers 301 and 302 may be, for example, an N-type chargegeneration layer and a P-type charge generation layer, respectively. TheN-type charge generation layer may be an organic layer that is dopedwith an alkali metal such as Li, Na, K, and/or Cs, and/or an alkaliearth metal such as Mg, Sr, Ba, and/or Ra. However, the embodiment ofthe inventive concept is not limited thereto. The P-type chargegeneration layer may be an organic layer including a P-type dopant.However, the embodiment of the inventive concept is not limited thereto.

The first hole control layer HCL1 may be disposed between the first subpixel electrode 110 and the first light emitting layer EML1. The secondhole control layer HCL2 may be disposed between the first chargegeneration layer 300 and the second light emitting layer EML2.

When the first sub pixel electrode 110 is an anode electrode layer,holes injected from the first sub pixel electrode 110 may reach thefirst light emitting layer EML1 via the first hole control layer HCL1.The holes generated in the first charge generation layer 300 may reachthe second light emitting layer EML2 via the second hole control layerHCL2.

Each of the first and second hole control layers HCL1 and HCL2 may bedivided into at least one region selected from a hole injection region,a hole transporting region, a buffer region, and an electron blockingregion. Each of the first and second hole control layers HCL1 and HCL2may have a single-layered structure formed of a single material, asingle-layered structure formed of a plurality of materials differentfrom each other, or a multi-layered structure including a plurality oflayers formed of a plurality of materials different from each other.

For example, each of the first and second hole control layers HCL1 andHCL2 may include at least one selected from a hole injection layercorresponding to a hole injection region and a hole transporting layercorresponding to a hole transporting region, or may be a single layerhaving a hole injection function and a hole transporting function at thesame time (e.g., by mixing a hole injection material and a holetransporting material in a single layer).

Each of the first and second hole control layers HCL1 and HCL2 may beformed of at least one selected from a hole injection material and ahole transporting material. The hole injection material and the holetransporting material may each independently be any suitable material.

The hole transporting material may include, for example, acarbazole-based derivative such as N-phenylcarbazole and/orpolyvinylcarbazole, a fluorine-based derivative, a triphenylamine-basedderivative such asN,N′-bis(3-methylphenyl)-N,N′-diphenyl-[1,1-biphenyl]-4,4′-diamine (TPD)and/or 4,4′,4″-tris(N-carbazolyl)triphenylamine (TCTA),N,N′-di(1-naphthyl)-N,N′-diphenylbenzidine (NPB), and/or4,4′-Cyclohexylidene bis[N,N-bis(4-methylphenyl)benzenamine] (TAPC), butis not limited thereto. The hole injection material may include, forexample, a phthalocyanine compound such as copper phthalocyanine,N,N′-diphenyl-N,N′-bis-[4-(phenyl-m-tolyl-amino)-phenyl]-biphenyl-4,4′-diamine(DNTPD), 4,4′,4″-tris(3-methylphenylphenylamino) triphenylamine(m-MTDATA), 4,4′4″-Tris(N,N-diphenylamino)triphenylamine (TDATA),4,4′,4″-tris{N-(2-naphthyl)-N-phenylamino}-triphenylamine (2TNATA),poly(3,4-ethylenedioxythiophene)/poly(4-styrenesulfonate (PEDOT/PSS),polyaniline/dodecylbenzenesulfonic acid (PANI/DBSA), polyaniline/camphorsulfonic acid (PANI/CSA), and/or polyaniline/poly(4-styrenesulfonate)(PANI/PSS), but is not limited thereto.

Each of the first and second hole control layers HCL1 and HCL2 may beformed through a process similar to that for forming the first andsecond light emitting layers EML1 and EML2. For example, each of thefirst and second hole control layers HCL1 and HCL2 may be formed byusing various methods such as a vacuum deposition method, a spin coatingmethod, a casting method, a Langmuir-Blodgett (LB) method, an injectprinting method, a laser printing method, and/or a laser induced thermalimaging (LITI) method.

Each of the first and second hole control layers HCL1 and HCL2 mayinclude a hole blocking layer corresponding to the hole blocking region.Here, each of the first and second hole control layers HCL1 and HCL2 mayinclude any suitable hole blocking material. Also, each of the first andsecond hole control layers HCL1 and HCL2 may further include a chargegeneration material.

The first electron control layer ECL1 may be disposed between the firstlight emitting layer EML1 and the first charge generation layer 300. Theelectrons generated in the first charge generation layer 300 may reachthe first light emitting layer EML1 via the first electron control layerECL1.

The second electron control layer ECL2 may be disposed between thesecond light emitting layer EML2 and the upper electrode 600. When theupper electrode 600 is the cathode electrode layer, the electronsinjected from the upper electrode 600 reach the second light emittinglayer EML2 via the second electron control layer ECL2.

Each of the first and second electron control layers ECL1 and ECL 2 maybe divided into at least one region selected from an electron injectionregion, an electron transporting region, and a hole blocking region.Each of the first and second electron control layers ECL1 and ECL2 mayhave a single-layered structure formed of a single material, asingle-layered structure formed of a plurality of materials differentfrom each other, or a multi-layered structure including a plurality oflayers formed of a plurality of materials different from each other.

For example, each of the first and second electron control layers ECL1and ECL2 may include at least one selected from an electron injectionlayer corresponding to an electron injection region and an electrontransporting layer corresponding to an electron transporting region, ormay be a single layer having an electron injection function and anelectron transporting function at the same time (e.g., by mixing aelectron injection material and an electron transporting material in asingle layer).

Each of the first and second electron control layers ECL1 and ECL2 maybe formed of at least one selected from an electron injection materialand an electron transporting material. For example, the electrontransporting material may include Tris(8-hydroxyquinolinato)aluminum(Alq3), 1,3,5-Tri(1-phenyl-1H-benzo[d]imidazol-2-yl)phenyl (TPBi),2,9-Dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP),4,7-Diphenyl-1,10-phenanthroline (Bphen),3-(4-Biphenylyl)-4-phenyl-5-tert-butylphenyl-1,2,4-triazole (TAZ),4-(Naphthalen-1-yl)-3,5-diphenyl-4H-1,2,4-triazole (NTAZ),2-(4-Biphenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (tBu-PBD),Bis(2-methyl-8-quinolinolato-N1,O8)-(1,1′-Biphenyl-4-olato)aluminum(BAlq), berylliumbis(benzoquinolin-10-olate (Bebq2), and/or9,10-di(naphthalene-2-yl)anthracene (ADN), but is not limited thereto.

For example, the electron injection material may include LiF, Lithiumquinolate (LiQ), Li₂O, BaO, NaCl, CsF, and/or Yb; metal halides such asRbCl and/or RbI; and/or materials in which the electron transportingmaterial and an insulating organo metal salt are mixed, but is notlimited thereto.

The organo metal salt may be a material having an energy band gap ofabout 4 eV or more. For example, the organo metal salt may include metalacetate, metal benzoate, metal acetoacetate, metal acetylacetonate,and/or metal stearate.

Each of the first and second electron control layers ECL1 and ECL2 maybe formed by using various methods such as a vacuum deposition method, aspin coating method, a casting method, a Langmuir-Blodgett (LB) method,an inject printing method, a laser printing method, and/or a laserinduced thermal imaging (LITI) method.

The first sub pixel SPX1 according to an embodiment of the inventiveconcept is not limited thereto and thus may variously change. Forexample, the first sub pixel SPX1 may include three light emitting unitsand two charge generation layers respectively disposed between the threelight emitting units.

Although the first sub pixel SPX1 has been described above, each of thesecond to fourth sub pixels SPX2 to SPX4 may have a structure similar tothe first sub pixel SPX1.

FIGS. 17A to 17D are cross-sectional views illustrating active tasks(acts) in a method for manufacturing the display panel according to anembodiment of the inventive concept.

Referring to FIG. 17A, the pixel circuit layer PC may be formed on thebase substrate BS, and the first insulation layer IL1 may be formed onthe pixel circuit layer PC. A plurality of driving contact holes CNT_Drmay be formed in the first insulation layer IL1. A portion of the pixelcircuit layer PC may be exposed by each of the driving contact holesCNT_Dr.

As illustrated in FIG. 17B, the first to fourth sub pixel electrodes110, 120, 130, and 140 may be formed on the first insulation layer IL1.As described above, one end of each of the first to fourth sub pixelelectrodes 110, 120, 130, and 140 may be disposed in a correspondingdriving contact hole of the driving contact holes CNT_Dr, and each ofthe first to fourth sub pixel electrodes 110, 120, 130, and 140 may beconnected (e.g., coupled) to the pixel circuit layer PC through thecorresponding driving contact hole.

The pixel defining layer PDL may be formed on the first to fourth subpixel electrodes 110, 120, 130, and 140. The pixel defining layer PDLmay cover a portion of each of the first to fourth sub pixel electrodes110, 120, 130, and 140. Thereafter, the first light emitting unit 200may be formed on the pixel defining layer PDL and the first to fourthsub pixel electrodes 110, 120, 130, and 140.

The first contact hole CNT1 may be formed in the first light emittingunit 200, between the first sub pixel area SPA1 and the fourth sub pixelarea SPA4. The first contact hole CNT1 may be formed by removing aportion of the first light emitting unit 200 disposed on the first subpixel electrode 110 to expose a portion of the first sub pixel electrode110. In an embodiment of the inventive concept, the layer portions to beremoved may be removed through laser drilling.

As illustrated in FIG. 17C, the first charge generation layer 300 may beformed on the first light emitting unit 200 to correspond to the firstsub pixel area SPA1. The first contact part 310 of the first chargegeneration layer 300 may be formed in the first contact hole CNT1 todirectly contact the portion of the first sub pixel electrode 110, whichis exposed by the first contact hole CNT1. The first extension part 320may horizontally extend from the first contact part 310.

The second charge generation layer 400 may be formed on the first lightemitting unit 200 to correspond to the second and third sub pixel areasSPA2 and SPA3, and the third charge generation layer 700 may be formedon the first light emitting unit 200 to correspond to the fourth subpixel area SPA4. The first to third charge generation layers 300, 400,and 700 may be insulated from each other, disposed on the same layer(e.g., on the first light emitting unit 200), and may be horizontallyspaced apart from each other. The second light emitting unit 500 may beformed on the first to third charge generation layers 300, 400, and 700.

The second contact hole CNT2 may be formed between the second and thirdsub pixel areas SPA2 and SPA3. The second contact hole CNT2 may beformed by removing portions of the second light emitting unit 500 andthe second charge generation layer 400 to expose an inclined surface 411of the second contact part 410 of the second charge generation layer400. In an embodiment of the inventive concept, the layer portions to beremoved may be removed through laser drilling.

As illustrated in FIG. 17D, the upper electrode 600 may be formed on thesecond light emitting unit 500. A portion of the upper electrode 600 maybe disposed in the second contact hole CNT2 to directly contact theinclined surface 411 of the second contact part 410, which is exposed bythe second contact hole CNT2.

As described above, the first charge generation layer may receive thefirst pixel voltage from the first sub pixel electrode, and the secondcharge generation layer may receive an upper voltage from the upperelectrode. As a result, the second light emitting unit may generatelight by the first electric field generated between the first chargegeneration layer and the upper electrode, and the first light emittingunit may generate light by the second electric field generated betweenthe second charge generation layer and the second sub pixel electrode.Thus, the driving voltage for driving the first and second lightemitting units may be reduced to improve the efficiency of the first andsecond light emitting units.

It will be understood by those skilled in the art that exampleembodiments described herein should be considered in a descriptive senseonly and not for purposes of limitation, and various modifications andvariations can be made in the present invention. While one or moreexample embodiments have been described with reference to the drawings,it will be understood by those of ordinary skill in the art that variouschanges in form and details may be made therein without departing fromthe spirit and scope of the present disclosure as defined by thefollowing claims and equivalents thereof.

What is claimed is:
 1. A display panel comprising: a base substrate; afirst sub pixel electrode on the base substrate; a second sub pixelelectrode on the base substrate and spaced apart from the first subpixel electrode when viewed in plane; a first light emitting unit on thefirst and second sub pixel electrodes, the first light emitting unitbeing provided with a first contact hole; a first charge generationlayer comprising a first contact part and a first extension partextending from the first contact part, the first contact part being inthe first contact hole and being coupled to a portion of the first subpixel electrode exposed by the first contact hole, and the firstextension part being on the first light emitting unit; a second chargegeneration layer on the first light emitting unit and overlapping thesecond sub pixel electrode when viewed in plane, the second chargegeneration layer being insulated from the first charge generation layer;a second light emitting unit on the first and second charge generationlayers, the second light emitting unit and the second charge generationlayer together being provided with a second contact hole; and an upperelectrode comprising a first upper electrode part and a second upperelectrode part extending from the first upper electrode part, the firstupper electrode part being in the second contact hole and being coupledto a second contact part of the second charge generation layer exposedby the second contact hole, and the second upper electrode part being onthe second light emitting unit.
 2. The display panel of claim 1,wherein, when viewed in plane, the first and second charge generationlayers are spaced apart from each other.
 3. The display panel of claim1, wherein, when viewed in a cross-section, the first and second chargegeneration layers are on the same layer.
 4. The display panel of claim1, wherein, when viewed in plane, the first extension part overlaps thesecond upper electrode part.
 5. The display panel of claim 4, furthercomprising a pixel defining layer configured to cover a portion of thefirst sub pixel electrode, wherein at least a portion of the firstextension part is on the pixel defining layer.
 6. The display panel ofclaim 4, wherein the first contact part is directly coupled to a portionof the first sub pixel electrode.
 7. The display panel of claim 4,wherein the second light emitting unit between the first extension partand the second upper electrode part is configured to generate anelectric field, and the second light emitting unit is configured togenerate light after being excited by the electric field, wherein thefirst extension part is configured to have substantially the samepotential as the first sub pixel electrode.
 8. The display panel ofclaim 1, wherein the second charge generation layer further comprises asecond extension part extending from the second contact part to overlapthe second sub pixel electrode when viewed in plane.
 9. The displaypanel of claim 8, wherein, when viewed in plane, the second upperelectrode part overlaps the second extension part.
 10. The display panelof claim 8, further comprising a pixel defining layer configured tocover a portion of the second sub pixel electrode, wherein at least aportion of the second extension part is on the pixel defining layer. 11.The display panel of claim 8, wherein an inclined surface of the secondcontact part exposed by the second contact hole is directly coupled tothe first upper electrode part.
 12. The display panel of claim 8,wherein the first light emitting unit between the second extension partand the second sub pixel electrode is configured to generate an electricfield, and the first light emitting unit is configured to generate lightafter being excited by the electric field, wherein the second upperelectrode part is configured to have substantially the same potential asthe second extension part.
 13. The display panel of claim 8, furthercomprising a third sub pixel electrode spaced apart from the first andsecond sub pixel electrodes when viewed in plane, wherein the secondcharge generation layer further comprises a third extension partextending from the second contact part to overlap the third sub pixelelectrode when viewed in plane.
 14. The display panel of claim 1,further comprising first and second color filters respectivelyconfigured to transmit light having colors different from each other,wherein, when viewed in plane, the first color filter overlaps the firstsub pixel electrode, and when viewed in plane, the second color filteroverlaps the second sub pixel electrode.
 15. The display panel of claim13, further comprising an auxiliary line between the second contact partand the base substrate, wherein the first upper electrode part iscoupled to the auxiliary line through the second contact hole.
 16. Thedisplay panel of claim 13, further comprising a fourth sub pixelelectrode spaced apart from the first to third sub pixel electrodes whenviewed in plane and a third charge generation layer overlapping thefourth sub pixel electrode when viewed in plane, wherein the thirdcharge generation layer is insulated from the first and second chargegeneration layers and is between the first and second light emittingunits.
 17. The display panel of claim 1, wherein at least one of thefirst and second charge generation layers comprises one or moreinorganic materials selected from Ag, Mg, Yb, Al, Ca, Li, and Cs.
 18. Amethod for manufacturing a display panel, the method comprising:providing a first sub pixel electrode on a base substrate; providing asecond sub pixel electrode on the base substrate and spaced apart fromthe first sub pixel electrode when viewed in plane; providing firstlight emitting unit on the first and second sub pixel electrodes;providing a first contact hole in the first light emitting unit toexpose the first sub pixel electrode; providing a first chargegeneration layer on the first light emitting unit and the first subpixel electrode and coupling the first sub pixel electrode to the firstcharge generation layer through the first contact hole; providing asecond charge generation layer on the first light emitting unit andspaced apart from the first charge generation layer when viewed inplane; providing a second light emitting unit on the first and secondcharge generation layers; providing a second contact hole in the secondlight emitting unit and the second charge generation layer; andproviding an upper electrode in the second contact hole and on thesecond light emitting unit and coupling a portion of the second chargegeneration layer exposed by the second contact hole to the upperelectrode through the second contact hole.
 19. The method of claim 18,further comprising providing a third sub pixel electrode on the basesubstrate, wherein the third sub pixel electrode is spaced apart fromthe first and second sub pixel electrodes when viewed in plane.
 20. Themethod of claim 19, further comprising: providing a fourth sub pixelelectrode on the base substrate; and providing a third charge generationlayer overlapping the fourth sub pixel electrode, wherein the fourth subpixel electrode is spaced apart from the first to third sub pixelelectrodes when viewed in plane, and the third charge generation layeris insulated from the first and second charge generation layers and isbetween the first and second light emitting units.
 21. The display panelof claim 7, wherein when the electric field is generated in the secondlight emitting unit, the electric field is not substantially generatedin the first light emitting unit.
 22. The display panel of claim 12,wherein when the electric field is generated in the first light emittingunit, the electric field is not substantially generated in the secondlight emitting unit.
 23. The display panel of claim 13, wherein thedisplay panel further comprises a pixel circuit layer on the basesubstrate and a first insulation layer on the pixel circuit layer, andwherein the third sub pixel electrode is coupled to the pixel circuitlayer through a contact hole provided in the first insulation layer. 24.The display panel of claim 15, wherein the auxiliary line and the secondcontact hole are between the second and third sub pixel electrodes, orthe auxiliary line and the second contact hole are between the third subpixel electrode and an edge of the display panel.
 25. The display panelof claim 1, wherein the first charge generation layer comprises a lowercharge generation layer and an upper charge generation layer, wherein atleast one of the lower and upper charge generation layers is an N-typecharge generation layer, and the other one of the lower and upper chargegeneration layers is a P-type charge generation layer.
 26. The displaypanel of claim 1, wherein the first and second charge generation layersare configured to supply electrons and/or holes to the second and firstlight emitting units, respectively.